1. Field of the Invention
This invention relates to laser systems which include an optical parametric oscillator to shift the wavelength of light emitted by the laser and, more particularly, to a laser system which utilizes the same optical resonator cavity for both the pump laser and the optical parametric oscillator.
2. Prior Art
Eyesafe laser transmitters of the type discussed herein typically include two resonator cavities. A first resonator cavity operates in conjunction with a pump laser operating at a pump frequency, and a second resonator cavity operates in conjunction with an optical parametric oscillator (OPO) which converts the pump frequency output of the laser to an eyesafe frequency. The two resonator configuration requires a total of three resonator mirrors for operation of the laser. The use of three resonator mirrors significantly complicates alignment of the mirrors.
In addition to alignment considerations, typical eyesafe lasers include a relatively short OPO cavity which results in high Fresnel numbers, thereby reducing the overall quality of the laser beam. Further, the spatial overlap of these cavities is often significantly limited by the present arrangements.
An uncoated U.sup.4+ :SrF.sub.2 Q switch aligned at Brewster's angle has been demonstrated in the resonator cavity of an Er:glass laser operating at an eyesafe frequency (1533 nm).